Neutron Detector Verification Using Cosmic Ray Background
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Solution Overview
Problem
There is a need for a method to verify the operational status and calibrate neutron detectors without using conventional neutron sources like AmBe or Cf-252, as natural radionuclides do not exist for neutron detection, and man-made sources pose administrative and radiation protection issues, leading to infrequent or absent checks of neutron detectors.
Innovation Solution
A method involving partially enclosing a neutron detecting device in a container with thermal neutron absorber material, exposing it to cosmic ray background neutron radiation, determining attenuated and operational count rates, and verifying status based on a ratio within a predetermined range, optionally using a neutron moderator device to enhance count rates and calibrate the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional neutron sources (AmBe, Cf-252) are used for verification, then the operational status can be verified, but administrative problems and radiation protection issues arise
Solution Approach 1:
The patent introduces an intermediary substance (neutron absorber material such as boron, cadmium, or gadolinium) that mediates between the cosmic ray background and the neutron detector. This intermediary creates a measurable signal difference that verifies detector functionality without requiring conventional neutron sources, thus eliminating administrative and radiation protection complexities while maintaining verification reliability
Solution Approach 2:
The patent creates an artificial neutron signal environment using neutron absorber materials that mimic the effect of conventional neutron sources. By placing these materials near the detector and utilizing cosmic ray interactions, the system produces a copy of the verification signal that would normally require AmBe or Cf-252 sources, thereby avoiding their associated administrative burdens
2Reliability
If neutron detectors are checked frequently, then operational status is maintained, but cost of ownership increases
Solution Approach 1:
The patent enables the neutron detector to perform self-verification by utilizing naturally occurring cosmic ray background radiation and neutron absorber materials. The detector monitors its own operational status by measuring the signal difference with and without the absorber material, eliminating the need for expensive external calibration services and reducing ownership costs while maintaining reliability
3Quantity of substance
If neutron detectors are not checked, then cost is reduced, but false failure messages may occur due to low background count rate
Solution Approach 1:
The patent applies preliminary anti-action by pre-placing neutron absorber materials in the detector's field of view before verification is needed. This creates a known baseline signal difference that prevents false failure messages, as the system can distinguish between normal low background counts and actual detector failures by comparing measurements with and without the absorber material in place
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the verification of operational status and calibration of neutron detectors, ensuring their reliability without the need for conventional neutron sources, thereby reducing costs and administrative burdens while maintaining radiation safety.
Implementation Method 1
a container having outer walls comprising a thermal neutron absorber material
Implementation Method 2
placing the neutron detecting device in direct contact with a neutron moderator device before exposing the neutron detecting device to neutron radiation originating from cosmic ray background
Data Source
Figure 1
Figure 2A~2C
Figure 3A
AI summary
A method of verifying the operational status of a neutron detecting device includes at least partially enclosing a neutron detecting device including a neutron detector in a container having outer walls comprising a thermal neutron absorber material, and determining an attenuated neutron count rate of the neutron detecting device. The method then includes removing the neutron detecting device from the container, exposing the neutron detecting device to neutron radiation originating from cosmic ray background, determining an operational neutron count rate of the neutron detecting device, determining a ratio between the operational neutron count rate and the attenuated neutron count rate, and verifying the operational status of the neutron detecting device if the operational neutron count rate is higher than the attenuated neutron count rate by at least a predetermined amount and the ratio is in a predetermined range.